Apple today announced the all-new Mac Pro will be available to order starting Thursday, December 19. Redesigned from the inside out, the all-new Mac Pro features the latest Intel Xeon processors, dual workstation-class GPUs, PCIe-based flash storage and ultra-fast ECC memory.

When I state something, it is fact, not a point to debate. The HD 7970 is not the same as a W9000/D700 .

D700 & W9000: 6GB of ECC RAM
HD 7970: 3GB of non-ECC RAM

D700 & W9000: 975mhz core speed
HD 7970: 3GB of 925mhz core speed

Apple and AMD call the D700 a "FirePro" because it is a workstation GPU with the associated hardware, firmware, and drivers.

While the W9000 has 6GB of RAM, I'm pretty sure it isn't 6GB of ECC RAM. I might be wrong, but I think Tahiti uses a "Virtual ECC" scheme in the same way NVidia does on the Quadro and Tesla cards. Those cards have 6GB of memory, but if you enable ECC, some of the memory is used for the extra ECC parity bits, leaving about 5.25GB of RAM. I think AMD does this with the FirePRO.

Also, D700 is likely clocked lower than the W9000. AMD advertizes 4 TFLOPS for W9000, Apple advertizes 3.5 TFLOPS for the D700, with an equal number of compute units. The memory clock is the same, though.

Finally, we simply don't know about the driver. Is it workstation-oriented like the Windows and Linux counterparts? Will it enable 30-bit color?

With the previous NVidia Quadro 4000 and 4800 cards for the Mac, workstation apps didn't run any better compared to consumer cards on MacOSX, even after NVidia took over driver development for Quadro drivers.

Of course, they did have separate drivers for Quadro, so hopefully this is the case.